Answer:
In the explanation
Step-by-step explanation:
Going to start with the sum identities
sin(x+y)=sin(x)cos(y)+sin(y)cos(x)
cos(x+y)=cos(x)cos(y)-sin(x)sin(y)
sin(x)cos(x+y)=sin(x)cos(x)cos(y)-sin(x)sin(x)sin(y)
cos(x)sin(x+y)=cos(x)sin(x)cos(y)+cos(x)sin(y)cos(x)
Now we are going to take the line there and subtract the line before it from it.
I do also notice that column 1 have cos(y)cos(x)sin(x) in common while column 2 has sin(y) in common.
cos(x)sin(x+y)-sin(x)cos(x+y)
=0+sin(y)[cos^2(x)+sin^2(x)]
=sin(y)(1)
=sin(y)
